Multiple bore wells having multibore tubing hangers and christmas trees often utilize multiple tubing strings or "purpose built" multiple bore completion or workover risers. These multiple tubing strings provide access to each individual bore but in deep water locations the multiple tubing strings are cumbersome. Also, the specially built riser to provide access to each individual bore for wirelining is very expensive.
U.S. Pat. Nos. 4,284,142 and 4,474,236 disclose structures of the purpose built type of multiple bore completion/workover risers. These structures provide the multiple bores extending completely through the structure so that access to each bore is available at the water surface.
U.S. Pat. No. 4,291,724 discloses a flowline switching apparatus in which access to a plurality of individual flowlines is provided for through flow line (TFL) tools from a single connection at the top of the structure. This disclosure involves the rotation of a cylinder structure with the flowline extending therethrough being curved to register with the individual bores as the cylinder is rotated.
U.S. Pat. No. 4,319,637 discloses an orienting system for running a multiple string tubing hanger for remote installation, such as an underwater wells.